U.S. patent application number 12/596154 was filed with the patent office on 2010-07-29 for haemodialfiltration method and apparatus.
Invention is credited to Juan Francisco Del Canizo Lopez.
Application Number | 20100187176 12/596154 |
Document ID | / |
Family ID | 39875115 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100187176 |
Kind Code |
A1 |
Del Canizo Lopez; Juan
Francisco |
July 29, 2010 |
HAEMODIALFILTRATION METHOD AND APPARATUS
Abstract
Device for haemodiafiltration, which comprises a first circuit
for a dialysis solution and a second circuit for blood, so that the
toxic substances from the blood flow pass into the dialysis liquid
within a haemofilter (11), a liquid pump (20) located upstream of
the haemofilter (11) in the first dialysis liquid circuit, is
adapted for injecting replacement liquid into the dialysis solution
flow after a blood pump (15) finishes pumping blood to the interior
of the haemofilter (11).
Inventors: |
Del Canizo Lopez; Juan
Francisco; (Madrid, ES) |
Correspondence
Address: |
LADAS & PARRY LLP
26 WEST 61ST STREET
NEW YORK
NY
10023
US
|
Family ID: |
39875115 |
Appl. No.: |
12/596154 |
Filed: |
April 23, 2007 |
PCT Filed: |
April 23, 2007 |
PCT NO: |
PCT/ES07/70081 |
371 Date: |
March 31, 2010 |
Current U.S.
Class: |
210/646 ;
210/219; 210/96.2 |
Current CPC
Class: |
A61M 60/268 20210101;
A61M 60/113 20210101; A61M 1/3441 20130101; A61M 1/3427
20140204 |
Class at
Publication: |
210/646 ;
210/219; 210/96.2 |
International
Class: |
B01D 61/26 20060101
B01D061/26; B01D 61/28 20060101 B01D061/28; B01D 61/32 20060101
B01D061/32 |
Claims
1. Device for haemodiafiltration, comprising a first circuit for
dialysis liquid and a second circuit for blood, so that the toxic
substances from the blood flow pass into the dialysis liquid in a
haemofilter (11); characterized in that the first dialysis liquid
circuit comprises a liquid pump (20), located upstream of the
haemofilter (11) in the first dialysis liquid circuit, adapted for
injecting additional liquid into the dialysis liquid flow after a
blood pump (15) has finished pumping blood to the interior of the
haemofilter (11).
2. Device according to claim 1; characterized in that the first
circuit for dialysis liquid comprises a first valve (21) upstream
of the liquid pump (20) and a second valve (19) downstream of the
liquid pump (20).
3. Device according to claim 2; characterized in that the first
circuit for dialysis liquid also comprises a third valve (18)
downstream of the haemofilter (11).
4. Device according to claim 1; characterized in that the second
circuit for blood comprises a first valve (14) upstream of the
blood pump (15) and a second valve (16) downstream of the
aforementioned pump (15).
5. Device according to claim 4; characterized in that the second
circuit for blood also comprises a third valve (17) downstream of
the haemofilter (11).
6. Device according to claim 2; characterized in that the liquid
pump (20) is a syringe pump (20).
7. Method for haemodiafiltration, comprising a first circuit for
dialysis liquid and a second circuit for blood, so that the toxic
substances from the blood flow pass into the dialysis liquid in a
haemofilter (11); characterized in that it comprises the stages of
injecting blood into the haemofilter (11) through a blood pump
(15), injecting additional liquid into the dialysis liquid that
flows through the first dialysis the first dialysis liquid circuit
through a liquid pump (20), located upstream of the haemofilter
(11) in the first dialysis liquid circuit, adapted for injecting
additional liquid into the dialysis liquid flow that enters the
haemofilter (11).
8. Method according to claim 6; characterized in that the passing
stage of the additional liquid added to the dialysis liquid flow to
the blood through a membrane that comprises the haemofilter
(11).
9. Control unit connectable to a haemodiafiltration device
according to claim 1; characterized in that the control unit is
adapted to perform a variation calculated at the flow of each of
the pumps (15, 20) respectively, in such a way that it allows the
opening and closing time of each of the valves (15 to 19, 21) to be
regulated so that the liquid added to the dialysis solution passes
into the blood flow.
Description
PURPOSE OF THE INVENTION
[0001] This invention refers to a method and device for performing
haemodiafiltration, which is a renal dialysis method that combines
haemodialysis and haemofiltration, in order to achieve a high
removal of substances with a high and low molecular weight.
STATUS OF THE TECHNIQUE
[0002] From patent EP0516152B1, a device is known for performing
haemodiafiltration, namely, an extra-renal purification technique
that combines two mechanisms: dialysis or diffusion and
ultrafiltration or convection.
[0003] The aforementioned device comprises two circuits; a dialysis
liquid is connected to a first circuit through the external chamber
of a haemofilter against the direction of the blood flow, which is
connected to a second circuit to maximize the difference in
concentration of the substances that one wishes to remove, in all
areas of the filter.
[0004] Therefore, a dialysis liquid is infused into the haemofilter
against the flow, which will be removed with the
ultra-filtering.
[0005] Consequently, a path of solutes with low molecular weight
takes place from the blood to the dialysis liquid due to the
difference in concentration, in addition to a high clearance of
water and solutes by the pressure gradient. In other words, it
filters blood, extracts liquid from the internal media, dialyses
and purifies solutes from the body.
[0006] The first circuit of the dialysis solution is regulated by a
set of pumps located upstream and downstream of the haemofilter,
respectively.
[0007] Analogously, the second circuit of the blood is also
regulated by a set of pumps located upstream and downstream of the
haemofilter, respectively.
[0008] The replacement liquid can be infused in the arterial line,
upstream of the haemofilter, pre-dilution, and in the vein line
that exits from the haemofilter, post-dilution.
[0009] Generally, the method most used is post-dilution. However,
this method has some disadvantages, such as the blood in the
haemofilter becoming very concentrated when a high amount of liquid
is extracted.
[0010] A consequence of the above is that the performance of
ultra-filtering decreases and an increase occurs in the resistance
to the path of the blood flow, which may lead to a poor flow and
the clotting of the second blood circuit; since the rate of
haemofiltration rises, the blood becomes concentrated in the
haemofilter, its viscosity increases and the hydraulic resistance
and risk of clotting of the same increases.
[0011] A consequence of the above is that the service life of the
haemofilter is reduced.
CHARACTERIZATION OF THE INVENTION
[0012] This invention seeks to resolve and reduce one or more of
the problems stated above, through a haemodiafiltration device as
is claimed in claim 1. Embodiments of the invention are established
in the subsequent claims.
[0013] A purpose of this invention is to extend the service life of
the haemofilter and avoid the decreased performance of the same
during its effective lifetime.
[0014] Another purpose of this invention is to decrease the risk of
blood clotting in the second blood circuit of the
haemodiafiltration device.
[0015] Yet another purpose of this invention is to decrease the
risk of obstruction of the filtering media, the semipermeable
membrane, which separates the two flows that enter and leave the
haemofilter.
BRIEF DESCRIPTION OF THE FIGURES
[0016] Now the devices that make up the invention will be
described, as an example only, referring to the attached drawings,
in which:
[0017] FIG. 1 shows in a flow chart a haemodiafiltration device
according to the invention,
[0018] FIG. 2 shows when a blood pump of the haemodiafiltration
device is empty according to the invention,
[0019] FIG. 3 shows when a liquid pump of the haemodiafiltration
device injects the fill liquid into the dialysis liquid circuit
according to the invention, and
[0020] FIG. 4 shows the blood pump of the haemodiafiltration device
full according to the invention.
DESCRIPTION OF THE INVENTION
[0021] In reference to FIG. 1, below there is a flow chart
schematically illustrated of a device used to perform
haemodiafiltration, which comprises a first circuit of the dialysis
solution regulated by the action of a first set of valves 18, 19,
21 and a pump 20 just like a syringe tube pump 20, which is located
upstream of the first dialysis circuit, i.e. before a haemofilter
11.
[0022] A second regulated blood circuit, also regulated by the
action of a second set of valves 14, 16, 17 and a pump 15, just
like a tube pump 15, which is located on the upstream side, i.e.
the arterial side of the second blood circuit before the
haemofilter 11.
[0023] Both the first and second circuit come into contact at the
haemofilter 11, which comprises a semipermeable membrane.
[0024] As has been mentioned previously, each circuit comprises at
least three valves 18, 19, 21, 14, 16 and 17, respectively,
distributed upstream and downstream of haemofilter 11.
[0025] Replacement liquid is injected through syringe pump 20, the
reinfusion process, of a solution that can be similar to the
dialysis solution in the blood through haemofilter 11 to
re-establish to its original volume.
[0026] To carry out reinfusion, the pulsating characteristics of
the tubular pump 15 are used, which cause the trans-membrane
pressure in the membrane of haemofilter 11 during haemofiltration
to not be constant, and may become quite absent at any moment.
[0027] The aforementioned pressure is highest during the systole of
blood pump 15 and practically zero during the diastole of the
same.
[0028] By taking advantage of this circumstance, one can carry out
the reinfusion process of the replacement liquid by using the
pressure gradient that is generated in the very membrane of the
haemofilter. In other words, during this time period, the flow
through the same is inverted, and if in this time period the
reinfusion liquid is added to the dialysis solution, said
reinfusion liquid passes into the blood flow, since the flow
through the membrane is inverted, i.e. a liquid path from the
dialysis solution to the blood flow takes place.
[0029] Based on FIGS. 1 to 4, we can explain the replacement liquid
path process to the blood flow through the haemofilter 11
membrane.
[0030] The starting situation is when the blood pump 15 is
completely full, the second outlet valve 16 is open and the third
blood stop valve 17 after haemofilter 11 is closed.
[0031] Simultaneously, the liquid perfusion pump 20 is completely
empty and the second outlet valve 19 is closed, with the first
replacement liquid stop valve 21 being open.
[0032] Under these conditions, the impulse of the blood pump 15
takes place. The volume moved by the aforementioned pump 15 enters
the blood chamber of haemofilter 11 and an equivalent volume of
plasma seeps through the membrane of the same and exits the liquid
outlet of the haemofilter through the third valve 18.
[0033] This plasma outlet causes the blood contained in haemofilter
11 to become concentrated as a function of the relationship that
exists between the ejection volume of blood pump 15 and the blood
chamber volume of haemofilter 11. See FIG. 2.
[0034] During the impulse process of blood pump 15, the replacement
liquid pump 20 has been filled with replacement liquid.
[0035] At that time, the blood inlet valve 16 and outlet valve 17
of the filter are closed and the replacement liquid inlet valve 19
and outlet valve 18 of the haemofilter are open, with the impulse
of liquid pump 20 starting, which at this first moment is used to
wash the dirty liquid that was just filtered. See FIG. 3.
[0036] Once a pre-determined volume of liquid has passed from the
scheduled wash, the third replacement liquid outlet valve 18 is
closed and the third blood outlet valve 17 of the haemofilter
opens.
[0037] The remaining volume of liquid moved by liquid pump 20, upon
finding itself with the closed first liquid stop valve 21 and the
third replacement liquid outlet valve 18, seeps towards the blood
flow through the membrane in the reverse direction.
[0038] If the volume that is injected with liquid pump 20 is
substantially similar to the volume of plasma that has been
previously ultra-filtered, the blood will recover its original
haematocrit within the same haemofilter 11 and at the same time, an
equivalent volume of blood will be replaced for the patient. See
FIG. 4.
[0039] Some advantages of the system are that the blood does not
increase its haematocrit within the capillary of haemofilter 11,
and therefore the hydraulic resistance of the same is lower.
[0040] As the haematocrit does not increase in the capillary of the
haemofilter 11 membrane, the risk of clotting is minimized.
[0041] Filtration at the haemofilter 11 membrane is done in the
direction of the blood flow towards the dialysis liquid and vice
versa, i.e. in both directions of the membrane, whereby it hinders
the depositing of platelets and erythrocytes in the pores of the
capillary, and therefore the obstruction of the same.
[0042] In this device, the direction of filtration at the membrane
is inverted in each cycle, with which the depositing of cells is
reduced, as is the obstruction of the membrane pores.
[0043] The coordinated operation of both pumps 15, 20 and of the
six valves 15 to 19 and 21 is controlled and regulated by a control
unit that receives information from a set of receivers distributed
over pumps 15, 20 and the six valves 15 to 19 and 21.
[0044] Said control unit is adapted to perform a variation
calculated at the flow of each of the pumps 15 and 20 respectively,
in such a way that it allows the opening and closing time of each
of the valves to be regulated so that the liquid added to the
dialysis solution passes into the blood flow.
[0045] The embodiments and examples stated in this report are
presented as the best explanation of this invention and its
practical application, and thus allow the experts in the technique
to put into practice and utilise the invention. However, the
experts in the technique will recognise that the description and
the above examples have been presented for the purpose of
illustration and as an example only. The description as explained
is not intended to be exhaustive or to limit the invention to the
exact described form. Many modifications and variations are
possible in light of the above instruction without going beyond the
intent and scope of the following claims.
* * * * *